Recently, a user has dramatically increased opportunities to use a video content other than viewing of TV (television) broadcasting because of development of the digital techniques and the Internet and popularity of video posting sites. The user enters a keyword at a video posting site such as YouTube (registered trademark) or a search site such as Google (registered trademark), and retrieves a desired content. Unfortunately, in this method, elements having no keyword cannot be retrieved. Accordingly, a method by which the video content can be retrieved more simply and securely has been examined. For example, there has been proposed a method in which other video content is retrieved directly from one video content. As a conventional method for retrieving other video content from one video content, a method has been disclosed in which a video content is retrieved using part of a region of one still picture that forms the video content (for example, see Patent Literature 1).